Abstract: A compiling and stapling system with a compiling station for receiving and stacking sets of printed sheets inputted in a defined direction of movement for compiling and stapling them along a sheet edge transverse that movement direction with a two-part stapler providing ejection of the stapled sets out through that two-part stapler in the same direction of movement. This stapler has a staple driving unit separate from its staple clinching unit with an unobstructed spacing between them providing for unobstructed feeding of the stapled sets completely through the stapler in between the two separate units. An interlocking system such as a solenoid retractable alignment pin normally interlocks the two units in correct alignment for cooperate stapling and clinching of the collated set. The interlocking system then automatically unlocks the two units to provide an unobstructed set output path between the two units in that same direction of movement as the input path to the system.